You just need to return the values computed when a==0 and when a!=0.
a=0
f=function(x,y,z=0) {
if (a==0) return(x[1]+x[2]+y)
if (a!=0) return(x[1]+x[2]+y+z)
}
> f(1:2,3)
[1] 6
>
Ravi.
----------------------------------------------------------------------------
-------
Ravi Varadhan, Ph.D.
Assistant Professor, The Center on Aging and Health
Division of Geriatric Medicine and Gerontology
Johns Hopkins University
Ph: (410) 502-2619
Fax: (410) 614-9625
Email: [EMAIL PROTECTED]
Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html
----------------------------------------------------------------------------
--------
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Dwayne Blind
Sent: Wednesday, March 12, 2008 1:59 PM
To: r-help@r-project.org
Subject: [R] default values
Dear R users,
I wrote the following toy example to explain my problem :
a=0
f=function(x,y,z) {
if (a==0) x[1]+x[2]+y
if (a!=0) x[1]+x[2]+y+z
}
f(1:2,3)
I have not specified z and I get an error. Although a=0, R seems to want to
know z because it's in the expression x[1]+x[2]+y+z.
So I tried to put a default value :
a=0
f=function(x,y,z=0) {
if (a==0) x[1]+x[2]+y
if (a!=0) x[1]+x[2]+y+z
}
f(1:2,3)
Why isn't it working ? Sometimes everything is fine even though a parameter
is not specified.
Thanks a lot.
[[alternative HTML version deleted]]
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
